1. Field of the Invention
The present invention relates to a television conference system for use during a multi-location television conference.
2. Description of the Related Art
In recent years, with the advent of ISDN (Integrated Services Digital Networks), digital networks have been widely used and television conference systems have become popular.
The television conference systems transmit image data and sound data among remote locations so as to hold conferences. Conventional television conference systems transmit image data and sound data between two locations (namely, point-to-point connection). Recently, to more effectively hold conferences, a multi-location television conference system as shown in FIG. 1 has gained public attention. The needs of multi-location television conference systems result from geographical distribution of offices (such as main office, works, laboratories, sales offices) of companies. In this situation, so as to reduce cost and time necessary for transmitting information, people, and materials, television conferences have been held among television conference terminal units disposed at remote locations.
FIG. 1 is a schematic diagram showing an overall construction of a multi-location television conference system that holds a television conference among conference rooms A, B, C, and D disposed at four locations.
In the drawing, reference numerals 1 to 4 refer to television conference terminal units disposed at the four conference rooms. Reference numeral 10 refers to a multi-location control apparatus disposed at a center station.
The television conference terminal units (that may be hereinafter referred to as terminal units) 1 to 4 each have a camera, a monitor, a microphone, an encoding unit, and so forth. Thus, the television conference terminal units each have input and output functions of image data and sound data. Image data and sound data of each conference room are sent to the center unit 10. The center unit 10 sends the image data and sound data to each of the television conference terminal units.
The center unit 10 receives image data and sound data from all the conference rooms, mixes all the sound data, sends the mixed sound data to the television conference terminal units 1 to 4, and distributes the image data to all the television conference terminal units.
In this multi-location television conference system, a monitor of the television conference terminal unit at each conference room (location) switches and displays images of other conference rooms (of at least one location). When a speaking location is detected, the image thereof is automatically displayed. Thus, the monitor of each conference room displays at least an image of a speaking location. (However, the monitor of a speaking location displays an image of a former speaking location.)
A switching and displaying type multi-location control apparatus that distributes an image of one conference room to television conference terminal units of other conference rooms is known. This multi-location control apparatus can be easily introduced because the television conference terminal units for use with the point-to-point connection type television conference system can be used as they are. Thus, the switching and displaying type multi-location control apparatus has been widely developed and fabricated.
Moreover, a multi-location control apparatus having a new station (NS)/past station (PS) designating mode is known.
Conventionally, an image switching operation in the NS/PS designating mode is automatically performed when the television conference terminal unit at each location is operated. Alternately, this operation is automatically performed when the multi-location control apparatus detects a speaking attendant. This function is referred to as the speaking attendant detecting function. With this function, the multi-location control apparatus distributes image data of the speaking location (NS) to the television conference terminal units at other locations. In addition, the multi-location control apparatus distributes the image data of the former speaking location (PS) to the television conference terminal unit at the speaking location (NS).
FIG. 2 is a schematic diagram showing an example of the operation of the NS/PS designating mode. In this drawing, a multi-location control apparatus 20 is connected to television conference terminal units 12A, 12B, 12C, 12D, and 12E disposed at five locations of conference rooms A, B, C, D, and E, respectively through a network.
In this television conference system, when an attendant speaks at the conference room A or an image switching and selecting operation for an image of the conference room A is performed at another conference room, the multi-location control apparatus 20 designates the conference room A to the NS mode and sends the image data of the conference room A to the television conference terminal units at other conference rooms B, C, D, and E (see a solid arrow of FIG. 2). In addition, the multi-location control apparatus 20 sends the image data of the conference room D that has been designated to the PS mode to the conference room A that has been designated to the NS mode (see a dotted arrow of FIG. 2).
FIG. 3 is a block diagram showing an overall construction of a multi-location television conference system having a multi-location control apparatus 110 that automatically designates the conference rooms A, B, . . . , and E to the NS/PS mode depending on detecting a speaking attendant and switches and controls image data to be distributed to the television conference terminal units 120A, 120B, . . . , and 120E.
As shown in FIG. 3, each of the television conference terminal units 120A to 120E comprises a plurality of microphones 121, a microphone mixer 122, a speaker 123, a sound control unit 124, a sound encoding and decoding unit (hereinafter referred to as sound CODEC) 125, a camera 126, a monitor 127, an image CODEC 128, and a multiplexing and demultiplexing unit (MUX/DMUX) 129. The microphones 121 are directed to attendants in a conference room. The microphone mixer 122 mixes outputs of the microphones 121. The speaker 123 outputs a sound of another television conference terminal unit 120. The sound control unit 124 performs an input/output sound switching operation, an echo removing operation, or the like so as to prevent the output sound of the speaker 123 from entering the microphones 121. The sound CODEC 125 encodes sound data received from the sound control unit 123 and decodes sound data sent to the sound control unit 123. The camera 126 photographs the entire scene of the conference room, attendants, and/or materials. The monitor 127 displays images of other conference rooms received from other television conference terminal units 120. The image CODEC 128 encodes image data photographed by the camera 126 and decodes encoded data to an image to be displayed on the monitor 127. The MUX/DMUX unit 129 multiplexes and demultiplexes an input signal and an output signal of the sound CODEC 125 and the image CODEC 128.
The television conference terminal units 120A to 120E with the above-mentioned construction are connected to the multi-location control apparatus 110.
The multi-location control apparatus 110 comprises a multiplexing and demultiplexing (MUX/DMUX) unit 111, a sound CODEC 112, a sound level comparator 113, a mixer 114, an image selecting unit 115, and a control unit 116. The MUX/DMUX unit 111 multiplexes and demultiplexes sound data and image data received from and sent to each of the television conference terminal units 120A to 120E. The sound CODEC 112 is connected to the MUX/DMUX unit 111. The sound level comparator 113 compares levels of sound signals received from the sound CODECs 112 of the television conference terminal units 120A to 120E. The mixer 114 mixes the sound signals compared by the comparator 113 and sends the mixed sound signal to the speaker 123 of each of the television conference terminal units 120A to 120E through the sound CODEC 112 and the MUX/DMUX unit 111. The image selecting unit 140 selects image data demultiplexed by the MUX/DMUX unit 111 and sends the demultiplexed image data to the monitor 127 of each of the television conference terminal units 120A to 120E. The control unit 116 sends a selecting signal to the image selecting unit 140 corresponding to the compared result of the sound level comparator 113.
In this related art reference, the levels of the microphones 121 of the television conference terminal units 120A to 120E are compared by the sound level comparator 113 of the multi-location control apparatus 110. The multi-location control apparatus 110 designates the television conference terminal unit that outputs the maximum sound level to the NS mode. The image selecting unit 140 selects image data received from the television conference terminal unit with the maximum sound level and distributes this image data to other television conference terminal units.
FIG. 4 is a block diagram showing an inner construction of the image selecting unit 140.
Image data of the conference rooms A, B, C, . . . , and X at n locations are input to the input terminal 141. The image data are sent to an NS selecting unit 142 and a PS selecting unit 143 that select one from n alternatives. The NS selecting unit 142 and the PS selecting unit 143 receive a selecting signal from the control unit 116 and send image data of conference rooms that have been designated the n NS/PS selecting units 144A, 144B, 144C, . . . , and 144X to the NS and PS modes.
The output terminals of the NS/PS selecting units 144A, 144B, 144C, . . . , and 144X are connected to respective image data output terminals 145 of the conference rooms A, B, C, . . . , and X so as to select and output image data of the conference rooms that have been designated to the NS mode or PS mode.
In the image selecting unit 140 with the above-mentioned construction, when the conference room A is designated to the NS mode and the conference room E is designated to the PS mode, the control unit 116 outputs a selecting signal of the image data of the conference room A to the NS selecting unit 142 and a selecting signal of the image data of the conference room E to the PS selecting unit 143. The NS selecting unit 142 and the PS selecting unit 143 select and output image data received from the conference rooms A and B to the NS/PS selecting units 144A, 144B, . . . , and 144X. The NS/PS selecting unit 144A selects and outputs the image data of the conference room E, which has been designated the PS mode. The other NS/PS selecting units 144B, 144C, . . . , and 144X receive image data of the conference room A, which has been designated to the NS mode, from the control unit 116 and selects and outputs the image data. Thus, the image of the conference room A, which has been designated to the NS mode, is displayed on the respective monitors at the conference rooms B, C, . . . , and X, which have not been designated to the NS mode. On the other hand, the image of the conference room E, which has been designated to the PS mode, is displayed on the monitor at the conference room A, which has been designated to the NS mode.
In the first related art reference, image data is displayed in a fixed display format regardless of the number of speaking locations. In other words, the number of images of speaking locations displayed on a monitor at each conference room does not vary. Thus, when the system displays an image of one location, even if there are a plurality of speaking locations, only an image of a main speaking location is displayed. On the other hand, when the system displays a plurality of locations at a time, even if there is one speaking location, divided screen images of listening locations are also displayed on the monitor.
Thus, a listening attendant of a conference needs a certain amount of time to knows who is speaking. In this situation, the reality of the conference is deteriorated.
A first object of the present invention is to provide a display system that allows each attendant of a television conference to easily know speaking locations with reality.
In the related art multi-location television conference system having the conventional NS/PS designating mode, when in conference rooms that have not been designated to the NS mode, a conference room is selected, since this selected conference room is designated to the NS mode, monitor images of other conference rooms are switched. On the other hand, in the system that automatically designates the NS mode when detecting a speaking attendant, whenever a speaking location (conference room) is changed, the monitor image data is automatically switched regardless of the intention of listening attendants. Thus, these attendants cannot continue to see images of other conference rooms other than those of speaking locations.
Thus, in the conventional multi-location control apparatus with the designating of NS/PS modes, attendants of other conference rooms cannot select images of conference rooms they want to see. When an attendant of another conference room changes the mode or speaks, the image thereof is automatically displayed on the monitor screens of other conference rooms. This automatic switching of images of conference rooms adversely affects the proceeding of the conference.
A second object of the present invention is to hold a television conference at multiple locations with reality similar to a real convention.
Since any related art references of multi-location television conference systems display only image data of a conference room, attendants of the conference cannot easily know who is speaking at what conference room. Thus, the conference cannot be smoothly progressed.
A third object of the present invention is to allow each attendant to easily know background information (such as conference room name, location name, name and title of speaking attendant, and the like) with respect to image data of a conference room displayed on the monitor screen.